All the Carver article accomplishes is to provide some evidence that not all THD, at levels commonly perceived to be problematic (ie, over 1%) may in fact be perceptible to the listener. It in no way proves that, say, all THD above this level will not be problematic.

THD is an aggregate ratio of the amplitude of the higher order harmonics produced when the signal is amplified to the amplitude of the fundamental frequency. It is the combination of certain harmonics, particularly of higher order harmonics (as higher order harmonics are thought to be more problematic) and not just the aggregate of the amplitude of said harmonics that matters. To make matters worse, I don't think there are set testing criteria for published manufacturer specs (ie, one manufacturer could be testing with an input signal at a constant 60 Hz sine wave, while another could be using source material with a different combination of frequencies). Also, various gain (input voltage), etc, may be used.

THD is sort of like the average FPS metric for gaming GPUs. It relates to performance in general and a high average FPS or a low THD is a good sign, but, as anyone following this site recently can attest, does not show the whole picture.

cynan wrote:To make matters worse, I don't think there are set testing criteria for published manufacturer specs (ie, one manufacturer could be testing with an input signal at a constant 60 Hz sine wave, while another could be using source material with a different combination of frequencies).

IEF specs test a 1kHz sine wave.

If you didn't live through the Carver Challenge when it happened you have no idea how badly it roiled the high-end hi-fi (it was still hi-fi back then) industry at the time.

He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people and eat out their substance.

Captain Ned wrote:If you didn't live through the Carver Challenge when it happened you have no idea how badly it roiled the high-end hi-fi (it was still hi-fi back then) industry at the time.

Why, then, are there any amplifiers above $700 nowadays?

Audiophilia Nervosa, but that also assumes that a 1985-vintage C-J Premier Four was the best-sounding amp of all time. Read the article closely. They picked a tube amp for the single reason that they never thought Carver could make transistors sound like tubes.

Don't even get me started on Peter Belt or Shun Mook.

He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people and eat out their substance.

There are $10,000 phono cartridges, $1,000 power/audio/HDMI/Ethernet cables, and $200 wooden replacement knobs for your volume control that supposedly improve the sound through some magical process that defies known science, that will make that $700 amp look like a bargain! Some people have convinced themselves that there's a difference, and clearly have more money than common sense. 99% of it is pure snake oil, and the remaining 1% isn't anywhere near worth the asking price unless you've got Warren Buffet or Bill Gates kind of money.

Edit: Don't believe me? How about a $15,000 phono cartridge! I've actually bought stuff from that place, but the most expensive item I've ever ordered from them was an Audio-Technica ML440, back when they could still be had for around $100 (they're apparently going for north of $200 these days, which is way more than I'd ever pay for a phono cartridge even if I still listened to a lot of vinyl).

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

I still get Stereophile Magazine. They do semi-annual "Recommended Components" issues. The last time I tried this experiment (last year sometime) a full system (turntable/tonearm/cartridge, CD/DAC, pre-amp, power amp, speakers) consisting solely of the highest-priced recommended components was in the vicinity of $750,000 and that's without snake-oil cables or other crap.

EDIT: I know people will think I'm crazy, but an analog (i.e. spinny black things) rig of $2K would keep me happy for infinity. The turntable/tonearm/cartridge combo is the only place where I'm willing to spend what many see as crazy money. If the source component doesn't correctly present the music, no amount of heroic downstream "fixing" is going to help.

Yes, I know. I get your complaints. It'll be a once per lifetime purchase. Calling me stupid may make you feel better, but that's all it'll accomplish. Besides, JBI knows how I cherish my vinyl.

He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people and eat out their substance.

Captain Ned wrote:I still get Stereophile Magazine. They do semi-annual "Recommended Components" issues. The last time I tried this experiment (last year sometime) a full system (turntable/tonearm/cartridge, CD/DAC, pre-amp, power amp, speakers) consisting solely of the highest-priced recommended components was in the vicinity of $750,000 and that's without snake-oil cables or other crap.

...for those people with Warren Buffet or Bill Gates kind of money I referred to in my previous post!

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

just brew it! wrote:...for those people with Warren Buffet or Bill Gates kind of money I referred to in my previous post!

And most of those over $100K components may sell 3-4 a year in a good year. Just reading the Stereophile reviews to get a grasp of the bucket-loads of money and engineering spent to wrestle down the slightest sonic bobbles (mainly in the mega-turntable reviews) is all I need.

Besides, there's one simple way to make a $1K turntable sound like a $150K turntable, but it sorta involves house design. If you're building a house, pre-plan where the stereo rack will be. Make sure that a concrete column comes from the cellar slab through the floor (through the floor straight to the rack is the key) to that point. You could have the Sex Pistols mosh pit in your living room and nothing would bounce. Ever. Got the idea from my college radio station that did exactly that underneath the 2 broadcast turntables given the propensity of college DJs' air guitar to get a bit sloppy and the counter becoming the not-so-air drum kit.

He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people and eat out their substance.

Captain Ned wrote:If you didn't live through the Carver Challenge when it happened you have no idea how badly it roiled the high-end hi-fi (it was still hi-fi back then) industry at the time.

Why, then, are there any amplifiers above $700 nowadays?

Different amps do sound different. While most may consider these differences minor or even unimportant (if they can detect them at all), they can help companies with savvy marketing departments convince enough people that their different = better. I think most, if not all of why amps sound different is chiefly due to how they handle, and under what circumstances, they produce distortion. Some amps have output stages that actually purposefully introduce sonic signatures that could probably just as easily be called distortion (but at a level that's probably hardly measurable over what was already there). As already mentioned in the thread, tube amps don't produce those nasty odd order harmonics nearly so frequently. On the other hand, you have people calling solid state amplifiers "cold" - this just means that, on the whole, solid state introduces less distortion. While the distortion being produced is minimal enough that you can't pick out a "problem", distortion at sub-perceptible levels can make a signal sound a bit more interesting. This is probably also most of the deal behind people collecting and rolling their own tubes, etc.

Added to the whole marketing thing is aesthetics. A nice 0.5" thick piece of aluminum billet on the face of a high-end (looking) amp, together with the rest of the enclosure, explains half of the $700 right there. And if you can make your $700 amp look similar enough to an amp that costs $2000, then why not sell yours for $1500?

cynan wrote:Added to the whole marketing thing is aesthetics. A nice 0.5" thick piece of aluminum billet on the face of a high-end (looking) amp, together with the rest of the enclosure, explains half of the $700 right there. And if you can make your $700 amp look similar enough to an amp that costs $2000, then why not sell yours for $1500?

That reminded me of an old strip from everyone's (well at least my) favorite geeky web comic, xkcd:

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

FireGryphon wrote:Is there a way to calculate how much wattage is running through your speakers at a given volume?

Unless you've got an amp with meters on the outputs or specialized test equipment, not easily.

But 20W RMS through a speaker with any sort of reasonable efficiency is gonna be pretty freakin' loud unless you're sitting a fair distance away.

For normal listening, yes, but it's fun to turn up the volume every once in a while, and you never know when I might listen to something demanding and want to avoid the trouble I encountered with my father's old Allison speakers...

DeadOfKnight wrote:Does anyone here have experience with both the Logitech Z906 5.1 Speakers and the Corsair SP2500 2.1 Speaker System? I am finding it difficult to choose between these two. I'm wondering if I shouldn't just stick with the 2.1 setup because I have limited space, but in the future I may have plenty of space and want to upgrade to 5.1. Of course, by then I might be able to afford a real high-quality sound system instead...

I'm all set for headphones. I got the Ultrasone Alienware Ozma 7; I'll probably cry when these finally die on me because you can't find them anywhere. Not the most comfortable for long sessions, but the sound is orgasmic.

High end "computer speakers" are basically "low end speakers" the best of the very best are still mediocre. You're far far better off buying real, actual bookshelf speakers, (4 or 5) using a second hand or cheap proper 5.1 home theatre amp and some wiring. and no, you don't need a subwoofer if you buy the right equipment (it helps though)

ludi wrote:More bluntly, 10% THD is so bad that it will sound like there's radio static in the signal, and the tweeters will very soon be dead.

This is a common misconception. 10% THD may or may not be objectionable, it may not even be audible at all. Simply put, by itself THD is essentially useless as a measure of perceived sound quality. See this classic Bob Carver article: http://thecarversite.com/yetanotherforu ... sts&t=4481

Let me rephrase: A 10% THD figured being quoted from a solid-state amplifier being driven to the absolute short-term limits of its power supply will be dominated by clipping distortion, and behave every bit as badly as indicated.

AbRASiON wrote:High end "computer speakers" are basically "low end speakers" the best of the very best are still mediocre. You're far far better off buying real, actual bookshelf speakers, (4 or 5) using a second hand or cheap proper 5.1 home theatre amp and some wiring. and no, you don't need a subwoofer if you buy the right equipment (it helps though)

And nowdays with almost nobody using CRTs any more, you don't need to worry about getting speakers with "magnetically shielded" drivers to prevent the speaker magnets from making your screen go all psychedelic on you. This was a major justification for using "computer" speakers back in the early days of multimedia-capable PCs. They may have sounded like crap, but at least they didn't hose your CRT!

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

ludi wrote:More bluntly, 10% THD is so bad that it will sound like there's radio static in the signal, and the tweeters will very soon be dead.

This is a common misconception. 10% THD may or may not be objectionable, it may not even be audible at all. Simply put, by itself THD is essentially useless as a measure of perceived sound quality. See this classic Bob Carver article: http://thecarversite.com/yetanotherforu ... sts&t=4481

Let me rephrase: A 10% THD figured being quoted from a solid-state amplifier being driven to the absolute short-term limits of its power supply will be dominated by clipping distortion, and behave every bit as badly as indicated.

You can only guess as to what it will sound like. I stand by my assertion.

Technically true, but experience counts for something. Admittedly I don't have too much experience with Class D troubleshooting, but unless the designer incorporated some fairly high-quality circuitry to soft-clip the output signal and/or auto limit the amplification level in realtime, without being intrusive under normal operating conditions, the output at 10% THD will be mangled pretty badly.

jihadjoe wrote:Can the Dayton T-amps in question handle a 4-ohm load? I scored a pair of Polk Audio TSI300s on the cheap but I'm now not quite sure what to drive them with.

According to Polk, those units present an 8-Ohm nominal load and have a respectable 90dB efficiency rating. They won't require massive amplifier power, but a decent quality receiver would be better.

At 90db sensitivity anechoic (as long as its the usual 1 watt (2.83V for 8 ohms), at 1 meter) is a fairly efficient speaker. The Dayton DTA-100a should offer plenty of power for all but the largest rooms and more than enough for near-field. If it sounds anywhere near the VIrtue T-amps I mentioned earlier, and you are only interested in a 2-channel, then it might be well worth the $90. Given that the DTA-100a can provide a solid 30W/channel of clean power, it will go almost as loud as most lower/mid range solid state amps. Note that a doubling in wattage equates to a 3 db increase in volume - which is noticeable, but hardly so. Therefore, 30W/channel, will sacrifice only about 5 db of volume compared to a 100W/channel amp. Hardly noticeable for most home applications.

The DTA-100a says not to use speakers that have a less than 8-ohm impedance (but your Polks are fine as stated). However, you can run 4-ohm speakers on most "8-ohm" specced amplifiers, you just have to watch the volume level. A 4-ohm speaker will draw more power at a given volume (gain or voltage) level than an 8-ohm speaker. This normally just means the amplifier will get hotter and start clipping earlier. There is really no such thing as a 4 or 8 ohm amp. This is just a manufacturer suggestion at what impedance the amp will run comfortably throughout most of its available gain.

FYI, for those interested in T-amps. As for as the DTA-100a and similar T-amps with imput voltage rated at 24-30V, I would recommend ditching the included switching power supply in favor of 2 12-volt SLA batteries in series (capacities of 5-10 Ah, depending on room). What the batteries will give you is an extremely high current - desirable in an amplifier PSU. It will also isolate you from any potential noise issues if you have problematic AC supply. You can then get a 24V battery charger that plugs into the wall for < $50. The one I have is a cheap switching unit, but, with my AC supply, it doesn't seem to add any perceptible noise, so I just leave it attached in series and turned on at all times - it only comes on once in a while. Letting the batteries charge a little bit at a time as soon as the voltage in the circuit drops just a little bit will extend the life of the batteries greatly too. 2 10 Ah batteries in series will also power a DTA-100a or similar T-amp all day long (like 12 hours plus) without being plugged in - great for tailgate parties!

DeadOfKnight, I was in the same predicament as you. There were people telling me to buy bookshelf speakers and an amp but I had limited space.

While it may be true that bookshelf speakers + amp is better, I picked up a set of Klipsch ProMedia 2.1 and couldn't be happier for the $100 I spent on them (cyber monday deal). I don't really like that there isn't a switch to shut off the set though but that's me trying to be critical. FYI: at idle the setup sips ~8.5W of power whereas my old setup did about ~4.5W (with off switch). I personally didn't want to pick up a 5.1 set because it sounded like more of a hassle and, again, space constraints. Anyway, music, videos and games all sound crisp and clear.

If you're not an audio enthusiast (like me) you're going to really like a quality 2.1 set of computer speakers. Plus, if you do want to eventually spend the money on an "enthusiast" setup you'll get the chance to see how much of an improvement it is over "enthusiast" computer speakers.

DeadOfKnight, I was in the same predicament as you. There were people telling me to buy bookshelf speakers and an amp but I had limited space.

While it may be true that bookshelf speakers + amp is better, I picked up a set of Klipsch ProMedia 2.1 and couldn't be happier for the $100 I spent on them (cyber monday deal). I don't really like that there isn't a switch to shut off the set though but that's me trying to be critical. FYI: at idle the setup sips ~8.5W of power whereas my old setup did about ~4.5W (with off switch). I personally didn't want to pick up a 5.1 set because it sounded like more of a hassle and, again, space constraints. Anyway, music, videos and games all sound crisp and clear.

If you're not an audio enthusiast (like me) you're going to really like a quality 2.1 set of computer speakers. Plus, if you do want to eventually spend the money on an "enthusiast" setup you'll get the chance to see how much of an improvement it is over "enthusiast" computer speakers.

Most bookshelves will give you better accuracy, but as you say, this may not be what you're after. I personally find most computer X.1 systems (with subwoofers) a little unappealing due to very sloppy mid-bass (and little actually bass below 40 or 50 Hz). I owned an original Klipsch ProMedia 2.1 that, at least at first, could be tweaked to sound pretty decent. The Logitech systems I've tried (Z680s and Z2300s) sound absolutely terrible with their sub. The satellites on the Z680s were pretty decent at what they did, but the sub, and integration with the sub was just abysmal (though it was loud).

As far as size goes, you don't need to large speakers. However, if you go with smaller bookshelves (especially with woofers below 5"), you'll likely be missing any sort of bass punch. If this is important to you, and room is an issue a computer subwoofer system may be your best bet. If accuracy is more important, you can get smallish bookshelves that still sound good.

One example are the Audioengine P4s, which can be had on sale for $200 or a bit less for the pair. They are only about 6" wide by 6" deep and about 9" tall. Build quality is great. I have a pair connected to a desktop T-amp, and it's great for nearfield or moderate sized room. These, together with the DTA-100a (and I'm sure they'd be great with a lower-powered amp for nearfield, such as this, as well) should get you an awesome 2.0 system for about $300. And you can always add a subwoofer later.

I was vascilatting between the DTA-100 and the APA-150, but eventually spotted an ad for an almost-new NAD C316BEE. Since it cost just slightly more than a new Dayton APA-150 I decided to bite the bullet and go for it. Needless to say I'm a very happy camper right now. The NAD pairs nicely with the Polk Audio TSI300s that I mentioned earlier, and despite being just a 2.0 setup the sound (yes, even the bass) is much better than my previous Klipsch Promedia v2.400s. I guess it is true that you won't know what's good until you hear for yourself. I was certainly quite satisfied with the various x.1 computer speaker systems I've had before, but not anymore.

The Frank Tusa track "Gypsy Song" has cellos playing with awesome detail on the lower frequencies, frankly quite revealing. A proper stereo 2.0 setup just has so much more detail than a computer-oriented 4.1, even one as good as my previous Klipsch Promedias.